This invention relates to synthetic, bioabsorbable, porous foam tissue scaffolds and to the repair and regeneration of dermal tissue.
There is a growing demand for foams for biomedical applications such as scaffolds for tissue engineering, wound healing dressing and other implantable wound healing, augmentation, and regeneration devices. Specifically these foams have been made from biocompatible polymers and have an open celled microstructure.
Open cell porous biocompatible foams have been recognized to have significant potential for use in the repair and regeneration of tissue. Early efforts in tissue repair focused on the use of biocompatible foam as porous plugs to fill voids in bone.
Several attempts have been made in the recent past to make tissue engineering scaffolds using different methods for dermal tissue. Animal derived materials are known for use as acellular scaffolds used in regeneration of skin. However, most approaches using biodegradable synthetic scaffolds or animal derived materials have involved cell expansion and seeding onto the scaffolds, resulting in an in-vitro cultured substitute for skin. These products have had mixed clinical success and are far from optimum. Such approaches have one or more drawbacks from a viable product standpoint in the way of, for example, limited shelf life, difficulty in handling and storage, and expense due to the difficult cell culturing process. Lyophilization lends itself to many advantages when processing thermally sensitive polymers. Further, it lends itself to aseptic processing methodologies for bio-medical applications, especially when using combinations of polymers with drugs or other bio-active agents such as growth factors, proteins etc.
While improved processes for making foams generally useful as scaffolds for tissue engineering are known, which processes utilize lyophilization under certain identified conditions, it would be advantageous to provide a lyophilization process for providing foams that are particularly well suited for use as tissue scaffolds in the repair and regeneration of dermal tissue, e.g. skin, and to provide foams having physicochemical properties suitable for use in the repair and regeneration of dermal tissue.
The present invention is directed to synthetic, biocompatible, bioabsorbable foam tissue scaffolds comprising physicochemical properties suitable for use in the repair and/or regeneration of dermal tissue and to methods of preparing such foams, which methods comprise preparing a homogenous solution comprising a synthetic, biocompatible, bioabsorbable, aliphatic, elastomeric copolymer comprising copolymerized xcex5-caprolactone and glycolide at a molar ratio of xcex5-caprolactone:glycolide ranging from about 30:70 to about 40:60 and a solvent in which the copolymer is soluble, wherein the homogenous solution comprises from about 4 to about 6 weight percent, and preferably about 5 weight percent, of the copolymer and about 95 percent by weight of the solvent, placing an effective volume of the homogenous solution in a mold or other device suitable for preparing foam tissue scaffolds suitable for use in repair and regeneration of dermal tissue, quenching the homogenous solution at a temperature and at a rate sufficient to provide foam tissue scaffolds suitable for use in repair and regeneration of dermal tissue, solidifying the solution to form a solid and removing the solvent from the solid to provide a biocompatible, bioabsorbable porous foam suitable for use in the repair and regeneration of dermal tissue.